Bacterial spoilage inhibited metal working lubricant compositions

ABSTRACT

METAL WORKING LUBRICANT COMPOSITIONS USED TO COOL AND LUBRICATE METAL IN CUTTING, GRINDING, ROLLING, DRAWING AND SIMILAR METAL WORKING OPERATIONS ARE PROTECTED AGAINST BACTERIAL SPOILAGE DURING USE BY THE PRESENCE OF 10 TO 3000 P.P.M. OF A TRIAZINE COMPOUND OF THE FORMULA:   1,3,5-TRI(R-)-HEXAHYDRO-S-TRIAZINE   WHEREIN R IS CH3-(CH2)M-O-(CH2)NN IS THE NUMBER 2 OR 3, AND M IS THE NUMBER 0,1,2 OR 3.

BACTERIAL SPOILAGE lNI-IIBITED METAL WORKING LUBRICANT COMPOSITIONS EarlE. Borchert, Valley View'Village, Ohio, assignor to Ferro Corporation,Cleveland, Ohio No Drawing. Filed Apr. 6, 1972, Ser; No. 241,843

. Int. Cl. C10m N06 US. Cl. 252-495 8 Claims ABSTRACT OF THE DISCLOSUREMetal working lubricant compositions used to cool and lubricate metal incutting, grinding, rolling, drawing and similar metal working operationsare protected against bacterial spoilage during use by the presence of10 to n is the number 2 or 3, and m is the number 0,1, 2 or 3.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to metal working lubricant compositions that in metal workingoperations will comprise an aqueous phase and an oil phase containingcertain unique inhibitors against bacterial spoilage during use.

Description of the prior art It is common practice in many metal workingopera tions to circulate 'aliquid over the metal surface being worked tocool and lubricate the surface and the cutting tool or other devicewhich is working the metal. Such metal working lubricant compositionsare used in the cutting, grinding, rolling, drawing and similar metalworking operations including metal pressing, wire drawing, metalextrusion and the like. Generally, the lubricant composition which iscirculated over the worked metal surface is a mixture of a dissolved oremulsified lubricant component in a large excess of water. The choice ofthe lubricant component is often determined by the degree of lubricationdesired at the metal surface, as well as the susceptibility of metalsbeing worked to corrosion under .the given operating conditions.Generally, the lubricant component will be an oil of hydrocarbon, animalor vegetable origin existing as an oil phase emulsified by a waterphase. In a typical metal working operation, the lubricant emulsion isformed by mixing the product referred to in the metal working trade as asoluble oil with a large excess of water. Soluble oils generally are amixture of lubricant oil with emulsifying agents, wetting agents andmodifying agents of various types to provide easy emulsifiability of theoil in water, a stable emulsion once formed and the desired cutting andcooling characteristics to the resulting lubricant, emulsion. Theemulsion may be a water-in-oil type, but more frequently it is of theoil-in-water type. A wide variety of emulsifying or wetting agents areused in compounding these soluble oils including alkanolamides, alkylsulfonates, arylsulfonates, sulfated amines and amides, ethxylatedalcohols, ethoxylated alk'yl phenols, fatty acid, soaps, glycerolesters,

United States Patent Ofice 3,791,974 Patented Feb. 12, 1974 glycolesters, sulfosuccinates, alcohol sulfates, sulfated fatty acids andesters, phosphate derivatives and sorbitan derivatives.

In keeping with the general usage in the metal working and relatedindustries, the basic composition from which the metal working lubricantemulsions are formed will be referred to hereinafter as soluble oil, theemulsions made by mixing such soluble oil with a large excess of waterwill be referred to as lubricant emulsion and all of these materialswill be generally referred to by the generic term metal workinglubricant composition.

Lubricant emulsions during use in metal working operations are subjectto a significant degree to microbial degradation. The organisms whichbring this about are very numerous and are universally present in theambient atmospheres and metal working systems in which the lubricantemulsions are used. The emulsions can become severely contaminated bysimple exposure to air after a few hours or days. Once present in theemulsion, the organisms start to grow and divide immediately and theirpopulation can increase rapidly. There may be hundreds of differentspecies present, each adept at some particular degradation and mostactive under certain specified conditions. In general, continuously usedwell-aerated systems at close to ambient temperatures degrade quicklyand are dominated by aerobic bacteria such as Psuedomonas, Alcaligenesand Achromo'bacter. Systems not wellaerated, intermittently used or witha slow turnover will also contain anaerobic organisms (such asClostridium and Desulfovidrio desulfuricans) and facutative anaerobicorganisms. These are responsible for sickening, clinging smells-theso-called Monday morning odors.

The most obvious visible evidence of microbial growth is the microbesthemselves. They appear as slimes and sediments wherever they areallowed to accumulate, and are also removed from systems as deposits incentrifugal or other separators. Also obvious are the objectionablesmells due to degradation products, usually accompanied by darkeningcolor.

The chemical changes which have taken place may affect lubricatingproperties and viscosity. They can also degrade additives included toincrease oil film strength, inhibit corrosion or the like.

The degradation of the emulsifying chemicals by the micro-organisms isof considerable engineering significance. The emulsion progressivelychanges from finely dispersed oil droplets in water to a coarsedispersion and eventually free oil separates.

Rapid corrosion of parts after machining is associated with bacterialcontamination of the oils and emulsions. A stable oil film no longerforms on the part machined and as any added corrosion inhibitor willalso be altered or depleted by the organisms, the result can be a verycostly accumulation of unusable corroded products.

Adverse effects produced by high microbial activity in lubricantemulsions include:

(a) Short oil life; costly oil changes; time loss during changes;excessive topping up with oil to maintain the emulsion strength;

(b) Poor surface finish; roll-slip in rolling steel and aluminum;corrosion on steel sheet;

(c) Short tool life; fouled grinding wheels; wheel burn;

(d) Excessive solid loads on filters and clarifiers; slimes anddeposits;

(e) Rapid corrosion after machining;

(f) Smells and discolorations.

The prevention of excessive microbial growth by the inhibitors is theprincipal means of minimizing the adverse, effects. Among the morewidely used anti-microbial additives are hexahydrol,3,5-tris(2-hydroxyethyl)-s-triazine andhexahydro-1,3,S-triethyl-s-triazine. The present invention involves thenovel use and unexpected superiority ofhexahydro-1,3,5-tris(alkoxyalkyl)-s-triazines.

A variety of other materials have been used as inhibitors againstbacterial action upon soluble oils and lubricant emulsions, e.g., see-U.S. 3,013,973.

The utility of soluble oils and lubricant emulsions would be advanced ifimprovements could be made in the prevention of bacterial spoilage ofthese materials. Accordingly, it is a principal object of this inventionto provide certain unique inhibitors against bacterial spoilage ofsoluble oils and lubricant emulsions, to provide improved metal workinglubricant compositions containing improved bacterial spoilage inhibitorsand to provide certain new and novel compounds useful as suchinhibitors.

Other objects and further scope of applicability of the presentinvention will become apparent from the detailed description givenhereinafter; it should be understood, however, that the detaileddescription, while indicating preferred embodiments of the invention, isgiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description. Itshould also be understood the foregoing abstract of the disclosure isfor the purpose of providing a non-legal brief statement to serve as asearchingscanning tool for scientists, engineers and researchers and isnot intended to limit the scope of the invention as disclosed herein noris it intended it should be used in interpreting or in any way limitingthe scope or fair meaning of the appended claims.

SUMMARY OF THE INVENTION Objects of the invention are attained, in part,by the provision of metal working lubricant compositions protectedagainst bacterial spoilage during use in metal working operations by thepresence of to 3000 p.p.m. of a triazine compound of the formula:

n is the number 2 or 3, and m is the number 0, 1, 2 or 3.

Objects of the invention are also attained, in part, by new methods ofinhibiting bacterial spoilage of metal working lubricant emulsionsnormally subject to bacterial spoilage by providing in such emulsionsbetween about 10 to 3000 p.p.m. of triazine compound of the foregoingformula.

According to one embodiment of the invention, oil soluble compositionsfor admixture with water to form a metal working lubricant emulsion areprovided comprising an aqueous phase and an oil phase, said compositionscontaining as an inhibitor against bacterial spoilage of said emulsionduring use in metal working operations a minor amount ofhexahydro-l,3,5-tris(alkoxyalkyl)-s-triazine in which the alkoxy moietycontains 1 to 4 carbon atoms and the alkyl moiety contains 2 or 3 carbonatoms and especially where the alkoxy moiety contains 1 to 2 carbonatoms and the alky1 moiety is CH CH or -CH CH OH In another embodimentof the invention, metal working lubricant emulsions comprise an aqueousphase, an oil phase and between about 50 to 2000 p.p.m. of ahexahydro-l,3,5-tris(alkoxyalkyl)-s-triazine in which the alkoxycontains 2 or 3 carbon atoms.

4 DESCRIPTION OF PREFERRED EMBODIMENTS The following details ofoperations in accordance with the invention and reported data illustratethe further principles and practice of the invention to those skilled inthe art. In these examples and throughout the remaining specificationand claims, all parts and percentages are by Weight unless otherwisespecified.

EXAMPLE 1 Preparation of l,3,5-tris(3-methoxypropyl)-shexahydrotriazineInto a closed reaction vessel equipped with internal stirrer, externalheating and cooling jacket and liquid inlet tube, there was charged 490parts formalin (37% HCHO) and 6 parts K 00 Through the inlet tube, therewas added 525 parts of 3-methoxypropylamine at a rate slow enough toallow the temperature of the exothermic reaction to be maintained withexternal cooling at 50- 55 C. After the completion of such addition, thereaction mixture was held at a temperature of 55 C. for 45 minutes.

Water present in the resulting reaction mass was removed by vacuumdistillation at a pressure of 20 mm. Hg with a heating temperature of 60C. The yield of crude product was 570 parts (95.5% of theory). A portionof the crude product was used as an inhibitor of bacterial spoilage in ametal working lubricant composition.

Another portion was purified by high vacuum distillation and the portion(91% of original crude) boiling at 130l43 C. at 0.03 mm. Hg wascollected as a clear white liquid (Ref. Index at 25 C., Na-D line=l.466)having a density of 0.99. When tested as a microbiologic inhibitor, itwas comparable in activity to the crude product.

EXAMPLE 2 Preparation of 1,3,5-tris(alkoxyalkyl)-s-hexahydrotriazinesUsing the general procedure described in Example 1 of the triazines ofthe invention were prepared. The prop erties of the compounds are givenin the following table:

TABLE 1 R R.I. D B.P. Yield --5 1.460 0.95 143-152 (0.06 mm.) 94 (90)1.459 0.97 123-130 (0.13 mm.) 88 (83) (OHz):OCH| 1.466 1.02 113-122 (0.2nun.) 87

Evaluation of bacterial spoilage inhibition properties A series oflubricant emulsions were modified by addition of certain triazinecompounds to evaluate the ability of the compounds to inhibit bacterialspoilage. The lubricant emulsions were prepared by diluting soluble oilswith tap water in a 1:40 ratio. About 1500 ml. of the resulting emulsionwas placed in a wide mouth glass jar and 1 ml. of an emulsion highlycontaminated with bacteria obtained from a commercial metal workingoperation was added as an inoculum. The jar was kept uncovered in air atambient temperature (2025 C.) and a gentle stream of air (unmeasured)was bubbled through the inoculated emulsion. Every 7 days a count wasmade of the microorganism population of the emulsion using standardclinical practice. When the count reached l 10"/cc., the test wasterminated and the number of days recorded as the criteria ofinhibition. This test when repeatedfor each compound produced theresults reported in the following table:

TABLE 2.-DAYS TO FAILURE OF COOLING OIL EMUL- SIONS CONTAINING VARIOUSADDITIVES 1 N 0 data available.

In Table 2, the einulsions were prepared from soluble oils identified asfollows:

Column X reports the days to termination of emulsion containing. 1000'11pm. of 1,3,5-triethyl-s-hexahydrotriazine (prior art compound ascontrol).

Column Y reports the days to termination of emulsion containing 1000p.p.m. of 1,3,5-tris(2-hydroxyethyl)-shexahydrotriazine (priorart'compound as control).

Column Z1 reports the days to termination of emulsion containing 1000p.p.m. of compound of Example 1.

Columns Z2, Z3 and Z4 report the days to termination of emulsionscontaining 1000 p.p.m. of hexahydro-l,3,5- tris (2methoxyethyl)-s-triazine, hexahydro-l,3,5-tris(2-ethoxyethyl)-s-triazine andhexahydro-1,3,5-tris(3-ethyoxypropyl)-s-triazine, respectively.

In the case of Z1, the tests were terminated after 210 days. In thecases of Z2, Z3 and Z4, the data given reflect the state of the oilsafter 77 days of testing.

Concentrations of the additives of this invention less than 1000 p.p.m.gives somewhat less protection. Thus, at 500 p.p.m., the additive Z1afforded 70 days of effective protection to emulsion A. Even at 250p.p.m., the additive of Z1 afforded commercially useful periods ofprotection for emulsions D, F and G.

Concentrations higher than 1000 p.p.m. (e.g. 2000 or 3000 p.p.m.)provide long-term protection. Oils will usually begin to deterioratefrom non-microbial causes after a while and it is generally uneconomicalto use concentrations in excess of 3000 p.p.m.

EXAMPLE 4 Further evaluation of inhibition properties A soluble oil wasprovided of the following composition:

Parts Heavy petroleum lubricating oil 90 Sodium petroleum sulfonateSodium naphthenate 3 Ethanol 1 This soluble oil was mixed with water ina 1:40 oil: water ratio to form an oil-in-water emulsion which wassterilized in an autoclave. Compounds to be tested as bacterial spoilageinhibitors were added in 50 p.p.m., '100 p.p.m., 500p.p.m'.and='1000p.p.m. to'aliquots of the sterilized emulsion forming aseries of emulsion test samples. To each sample was added 0.1% of aninoculum (emulsion heavily contaminated with bacteria obtained fromindustrial metal working operation). The samples were allowed to standat ambient temperature in covered jars for 48 hours. A transfer of adrop of each sample was then made using a 4 mm. wire loop to nutrientagar plates. The plates were incubated and checked for evidence ofbacterial growth at 24-hour intervals up to 72 hours. A sample to whichno inoculum was added (designated Control 1) and another sample to whichinoculum was added but no inhibitor (designated Control 2) weresimilarly processed for comparison. The data produced by the test arereported in the following table:

TABLE 3 Sample 50 500 1, 000

N N N N 48 N N N L L 24 48 The success of the invention is due to thediscovery of critically superior properties for the specific class oftriazines defined above as inhibitors for bacterial spoilage of metalworking lubricating compositions. A preferred inhibitor of the inventionis 1,3,5-tris(ethoxy-ethyl)-shexahydrotriazine. Other inhibitors of theinvention include the corresponding methoxyethyl, 3-methoxypropyl,3-ethoxy propyl, propoxyethyl, propoxypropyl, butoxy ethyl andbutoxypropyl compounds. Mixtures of two or more may be used.

The quantity of inhibitor compound provided in the lubricant emulsioncan be varied and will depend, at least in part, upon the use-lifedemands of the metal working operation employing the emulsion. Mostsatisfactory results are obtained when the emulsion contains betweenabout 10 to 2000 p.p.m. of the inhibitor. It may be added directly tothe ultimate emulsion or to the soluble oil from which the emulsion isprepared by mixture with water. Generally, the emulsion will contain 25to 100 parts of water for each part of soluble oil and the inhibitorcontent of the soluble oil will vary accordingly, e.g., 1 to 20 parts ofinhibitor in each 100 parts of soluble oil, especially 1 to 5%inhibitor. Preferred soluble oils of the invention will have thefollowing formulations:

Percent Organic lubricant 75-90 Emulsifying agent 5-20 Inhibitor l-SOther additives 0-15 The bacterial spoilage inhibition methods of theinvention are particularly useful with lubricant emulsions that containan organic lubricant, but they may also be applied to metal workinglubricant compositions that comprise an inorganic base, e.g.,polyphosphates. The metal working industry divides these compositionsinto three general categories, i.e., petroleum base, synthetic base andinorganic base. Commercial examples of petroleum base include CitgoCoolant, Vantrol, Sun Seco, Texaco Soluble C, Enco Kutwell and ShellDromis. Commercial examples of synthetic base include Trim, MonroeBluecut, Chemtool, Lusol and Primecut. A

commercial example of inorganic base is Norton Wheelmate.

Petroleum base soluble oils typically employ petroleum sourcelubricating oils, e.g., mineral oil, naphthene base distillate oil,paratfin wax and equivalent oils and waxes. Synthetic base soluble oilsmay employ fatty acid soaps, organic amines, organic borates, vegetableoils and fats, animal oils and fats, vegetable or insect waxes.Combinations of these are frequently employed, e.g., 90% mineral oil and10% oleic acid or 70% tallow, 28% parafiin wax and 2% beeswax.

A wide variety of emulsifying agents are used in forming the solubleoils. General classes have been delineated hereinbefore. Frequently,they are anionic, but may also be non-ionic, cationic or combinations.Specific examples of emulsifying agents include sodium sulfosuccinate,sodium alkylphenoxypoly(ethylenoxy)ethyl sulfate, polyoxyethylenemonolaurate, polyethoxylated quaternary ammonium chlorides, esters ofethoxylated sorbitol, ethoxylated nonylphenol, sodium lauryl sulfate,sodium dodecylbenzenesulfonate, 'glyceryl monostearate, quaternaryammonium salts of alkylphosphoric acids, lauryl dimethyl amine oxide,coconut acid diethanolamide and similar emulsifiers, e.g., seeMcCutcheons Detergents and Emulsifiers Annual.

Additives include rust inhibitors, Wetting agents, defoamers, graphite,solvents, dyes, viscosity modifiers, and various other agents used tomodify the machining effect, stability, color, foaming or otherproperties of the soluble oils or the lubricant emulsions made fromthem.

Many examples of soluble oils, lubricant emulsions and their ingredientscan be found in the literature and patents, e.g., see US. 3,013,973;3,429,909 and 3,442,805.

The data and information reported above demonstrate that the class oftriazine compounds as hereinbefore defined provide exceptionalprotection to metal working lubricant compositions against bacterialdegradation. The resulting emulsion preservation methods are applicableto the total spectrum of soluble oils and lubricant emulsons.

The embodiments of the invention in which an exclusive property or rightis claimed are defined as follows:

1. A soluble oil composition for admixture with water to form a metalworking lubricant emulsion comprising an aqueous phase and an oil phase,said composition containing a. lubricating oil, an emulsifying agent andas an inhibitor against bacterial spoilage of said emulsion during usein metal working operations between about 1 and by weight of ahexahydro-1,3,5-tris(alkoxyalkyl)striazine in which the alkoxy moietycontains 1 to 4 carbon atoms and the alkyl moiety contains 2 or 3 carbonatoms.

2. A soluble oil composition for admixture with water to form a metalworking lubricant emulsion comprising an aqueous phase and an oil phase,said composition consisting essentially of the following ingredients inabout the percentages by weight indicated:

Percent A lubricating oil 75-90 Emulsifying agent 5-20 Bacterialspoilage inhibitor 1-5 8 wherein said inhibitor is ahexahydro-l,3,5-tris(alkoxyalkyl)-s-triazine in which the alkoxy moietycontains 1 to 4 carbon atoms and the alkyl moiety contains 2 or 3 carbonatoms.

3. The soluble oil composition of claim. 1 wherein said alkoxyalkylmoiety is selected from the group consisting of methoxypropyl,ethoxy'propyl, ethoxyethyl, methoxyethyl and butoxypropyl. I

4. A metal working lubricant emulsion comprising a continuous aqueousphase having dispersed therein as a discontinuous oil phase alubricating oil, said emulsion containing an emulsifying agent andbetween about 10 to 3000 p.p.m. of ahexahydro-l,3,5-tris(alkoxyalkyl)-striazine in which the alkoxy moietycontains l to 4 carbon atoms and the alkyl moiety contains 2 or 3 carbonatoms.

5. The emulsion of claim 4 wherein said aqueous phase amounts to about25 to 100 parts for each part of the oil phase.

6. The emulsion of claim 5 which contains about 5 to 20 partsemulsifying agent for each 100 parts of lubricating oil. I

7. The emulsion of claim 6 wherein said lubricating oil is a minerallubricating oil.

8. A soluble oil composition for admixture with water to form a metalworking lubricant emulsion comprising a continuous aqueous phase and adiscontinuous oil phase, said emulsion exhibiting low tendency towardbacterial spoilage in use as a metal working lubricant, said compositionconsisting essentially of the following ingredients in about thepercentage by weight indicated:

Percent Mineral lubricating oil -90 Emulsifying agent 5-20 Bacterialspoilage inhibitor 1-5 wherein said inhibitor is ahexahydro-1,3,S-tris(alkoxyalkyl)-s-triazine in which the alkoxyalkylgroup is selected from the group consisting of methoxypropyl,ethoxypropyl, ethoxyethyl, methoxyethyl and butoxypropyl.

References Cited UNITED STATES PATENTS 2,701,187 2/ 1955 Andress 44--633,228,829 1/1966 Wolf et al. 25249.5X 3,408,843 11/ 1968 Treat 252-495 XFOREIGN PATENTS 2,004.678 11/ 1969 France.

WARREN H. CANNON, Primary Examiner US. Cl. X.R. 72-42; 424249

